DE102004027130A1 - Flow sampling for determination of assay results - Google Patents

Abstract

An assay result reading apparatus for reading the result of an assay performed using a liquid transport carrier may include at least one light source capable of emitting light incident on at least one of two or more spatially separated regions of the carrier, a photodetector thus arranged in that it is capable of detecting light emitted from each of the two zones and generating signals indicative of the presence or absence of a liquid sample in the respective zone, and including a calculation circuit. The calculation circuit may respond to the signals to calculate a flow rate for a liquid flowing along the support, compare the calculated flow rate to upper and lower limits, and discard the assay result if the calculated flow rate is outside the upper and lower limits.

Description

Environment of invention

Of the The subject matter disclosed concerns assay readers for the measurement of analytes. In particular, it relates to electronic readers for use with assay test strips using optical flow measurement methods.

background the invention

Analytical devices suitable for testing analytes at home are now widely available commercially. An immunoassay device suitable for this purpose for the measurement of the pregnancy hormone human chorionic gonadotropin (hCG) is sold by Unipath under the brand name CLEARBLUE ^® and is in the EP 291 194 disclosed.

The EP 291 194 discloses an immunoassay device comprising a porous support comprising: a particulate labeled specific binding reagent for an analyte, the reagent being free to move when in the wet state; and an unlabeled specific binding reagent for the same analyte, this reagent is immobilized in a detection zone or test zone downstream of the unlabeled specific binding reagent. A fluid sample suspected of containing analyte is applied to the porous support, after which it interacts with the particulate-labeled binding reagent to form an analyte-binding partner complex. The particulate label is colored and is typically gold or a colored polymer, for example latex or polyurethane. The complex then migrates to a detection zone where it forms another complex with the immobilized unlabeled specific binding reagent, whereby the extent of the analyte present can be detected or observed. Due to the nature of the binding reactions that take place, it is necessary to wait until a certain period of time after the test has begun to elapse to read the result. This is particularly important for a visual semiquantitative test type in which the detection zone or reading line evolves over time.

Various Methods for timing the result were used for commercial Devices proposed, including instructions to the user to wait for a certain time before reading the assay result. Close other procedures a signal that is generated after a certain period of time has elapsed, as in our co-pending Application No. PCT / EP03 / 00274 is disclosed, the signal informing the user that the Assay result should now be read.

As a control and to ensure the proper functioning of the device, a control zone is usually provided downstream of the metering zone. A third binding reagent capable of binding to the first labeled reagent is immobilized in this control zone so that, in the absence of analyte, the user is able to verify that the test was performed correctly. The EP 653 625 discloses a lateral flow assay test strip for use in combination with an assay reader wherein the extent of binding of particulate label is determined optically. It is also from the US 5,580,794 It is known to provide an integrated assay device and lateral flow assay test strips, the result being determined optically using reflectance measurements.

The US 5,837,546 discloses a method of automatically starting an immunoassay device, wherein a lateral flow carrier is provided with additional electrodes which sense the presence of liquid on the test strip and a signal is generated which turns on the sampling electronics. Because of the nature of a lateral flow type assay that requires the release of a labeled particulate binding reagent, fluid flow along a support (typically porous), and trapping of the analyte complex in the detection zone, it is desirable to optimize the properties of the porous support.

The pore size of the carrier is an important consideration and is preferably chosen to be between 1-12 μm. The carrier is suitably nitrocellulose, the pore size of which may vary in part due to the manufacturing process. The assay device may additionally have a wick in fluid communication with the carrier which serves to collect the fluid sample and the carrier typically comprises two pieces of different materials. Nitrocellulose becomes more typical used as the support material for the assay strip and has considerable advantages over conventional strip materials such as paper due to its natural ability to bind proteins without the need for prior sensitization. To optimize the assay, the nitrocellulose is typically subjected to a number of treatments prior to use which include the use of blocking agents such as polyvinyl alcohol and the use of soluble glazes such as sugars to enhance the release of the labeled reagent.

The Inventors of the present invention have observed that the flow rate of liquid along the porous carrier may vary from test to test. In some cases, the wearer has a tendency to be flooded to become, i. the liquid front wanders along the carrier at a faster speed than normal. Was reversed in some cases noticed that the liquid front along the carrier moving at a much slower speed than normal, so that the carrier In some way is blocked. It was found out that the different types the liquid flow rate behavior lead to inaccurate results can.

by virtue of the inconsistent nature of the materials used for both the wick as well as the porous membrane can be used, the optimal time (after applying the Fluid sample) be variable for reading the result.

in the Interest in providing devices that are more accurate in themselves and more reliable are, would be it desirable alternative or additional Provide control features that would be able to do that Extent and / or the speed with which the liquid sample along the porous carrier wandered, determine, and discard such measurements, if it was determined that the flow rate is outside predetermined limits falls.

It would also be desirable provide a method in which the optimal time to read the Result reliable and repeatable.

Summary the invention

The The present disclosure provides an assay device in some embodiments ready to be a reader for use in conjunction with a lateral flow test strip which is capable of quantitating optically analyte concentrations and / or qualitatively with a high degree of reliability and accuracy to eat.

The The present disclosure also provides an assay reader, in particular one for use in conjunction with a lateral flow test strip, as well as a method for performing an analyte measurement, wherein the extent and / or the liquid flow rate along the test strip and where the final assay result can be discarded if it is determined that the liquid flow rate outside falls from certain predetermined limits.

In some embodiments includes an assay result reading device for reading the result of a Assays performed using a liquid transport carrier at least one light source capable of incident light on at least one of two or more spatially separate zones of the carrier to emit a photodetector arranged such that he is capable is to detect light emitted from each of the two zones and generate signals indicating the presence or absence a liquid sample in the respective zone, and a calculation circle, the responded to the signals to the flow rate for a liquid, along the carrier flows, to calculate the calculated flow velocity with upper and lower limits, and to discard the assay result, if the calculated flow rate outside the upper and lower limits.

In some embodiments, a method of assaying for an analyte of interest in a fluid sample includes placing a fluid transport carrier relative to an assay result reader, the carrier having at least two spatially separated zones, the reader comprising a housing having at least a light source and at least one photodetector, and the support is arranged such that the at least one light source emits light onto at least one of the zones, and so that light radiating from at least one of the zones is incident on the photodetector; Applying and introducing the liquid sample onto or into the liquid transport carrier; Be calculating the flow rate of the fluid sample along the carrier in response to signals generated by the at least one photodetector indicating the presence or absence of the fluid sample in a respective zone; and determining if the calculated flow rate is within predetermined acceptable limits.

The liquid transport carrier preferably comprises a porous carrier, such as a lateral flow assay test strip of the kind well known to those skilled in the art. Alternatively, the liquid transport carrier may be a capillary filling chamber, channel or the like (eg as shown in FIG US 6,113,885 disclosed). The liquid transport carrier may be an integral part of the assay result reading device, eg, in the manner described in U.S. Pat US 5,580,794 is disclosed. In such an embodiment, the combined reader / liquid transport carrier would typically be disposable. Alternatively, the liquid transport carrier may be a separate ingredient that is normally introduced into the assay result reader during the course of performing an assay. In this last embodiment, the liquid transport carrier (typically a lateral flow assay test strip) would generally be inexpensive and disposable after a single use, while the assay result reading device would be reusable and relatively expensive.

Summary the figures

1 FIG. 13 is a perspective view of one embodiment of an assay result reading device in accordance with the present disclosure; FIG.

2 FIG. 12 is a block diagram schematically illustrating some of the internal components of the embodiment of the reader incorporated in FIG 1 is shown; and

3 - 5 are graphs showing various signals originating from different sections of a test strip placed in the reading device incorporated in the 1 and 2 is shown, and their variation over time.

detailed Description of the invention

Around To exclude doubt becomes explicit indicated that any of the features referred to herein as "preferred," "desirable," "suitable," "advantageous," or the like described in one embodiment in combination with any other feature so described or features can be used or they can be alone be used except the context makes it different.

In describing the various embodiments, a number of terms are defined as follows:
"Liquid sample" refers to any liquid material suspected of containing the analyte of interest. Such samples may include human, animal or human-made samples. Typically, the sample is an aqueous solution or biological fluid.

Examples for biological liquids shut down Urine, blood, serum, plasma, saliva, interstitial fluid etc., one. Other samples that can be used include water, Food products, soil extracts and the like for carrying out industrial, environmental or food production assay as well like medical diagnostic assays, a. In addition, a solid Material suspected of containing the analyte as A test sample can be used once it is modified to a liquid Medium to form, which may include further treatment, to release the analyte.

Everyone suitable analyte of interest or analytes can be measured become. Analytes of particular interest include proteins, Haptens, immunoglobulins, hormones, polynucleotides, steroids, drugs, Agents more infectious Diseases (e.g., of bacterial or viral origin) such as Streptococcus, Neisseria and Chlamydia, drugs and biological markers such as cardiac markers etc., one.

typically, are the disclosed assay score reading devices and methods adapted to perform a diagnostic assay, i. for information about the health status of a single mammalian (typically one to receive human) subject.

It is preferred, the rate of progression of the fluid sample (rather than the extent of it) along the liquid transport carrier to calculate.

suitably becomes the flow rate calculated between two zones on the liquid transport carrier, so the presence of the liquid sample in, or a passage through, a first, upstream Zone is detected, as well as the presence of the liquid sample in, or a passage through, a second downstream Zone is detected. When the distance between the two zones is fixed is and / or is known, the relative or absolute flow rate the fluid sample simply by measuring the amount of time between detection the liquid sample in the first and the second zone elapses.

in principle can the first and second zones lie somewhere on the liquid transport carrier, so could for example, the first zone at the extreme upstream End, and the second zone could at the extreme downstream lying at the end. The distance between the two zones (and thus the migration time of the liquid sample) can be any that is appropriate and of which it is likely that them from the nature of the analyte to be determined and the physical Dimensions and properties of the liquid transport carrier depends. For example the liquid transport carrier can do one or more microfluidic channels optionally having one or more different microfluids Elements, such as separating agents for red blood cells, time barriers or means for controlling the flow rate all of which affect the migration speed of the sample become. In practice, it is desired that the two zones have a separation, so that at normal flow rates a sufficiently accurate flow rate within the time frame of the assay can be calculated to the Assay process or the assay result determination not to delay. For one Assay for the detection and / or quantification of the pregnancy hormone hCG, would be a desired one Time for example between 5 and 60 seconds.

advantageously, is the presence of the fluid sample in, or a passage through, one or more additional Detected zones on the liquid transport carrier. This allows a more accurate calculation of the flow rate. A big number of flow rate calculation zones can be advantageous if the acceptable range of flow rates rather tight, or if the flow rate in different Vary sections of the liquid transport carrier can (for example, if there are sections with different flow properties, for example due to the inclusion of microfluidic elements gives).

Furthermore It allows the provision of a variety of "test zones", to verify that the liquid sample progress through each of the zones in the expected order, while the user is at a non-normal flow pattern warned when the liquid sample in a downstream zone before detection in a particular upstream Zone is detected. Such non-normal flow patterns may occur, for example, if a porous one carrier flooded by liquid samples becomes ("excessive sampling").

If the calculated flow velocity outside the predetermined acceptable limits, then the result of the assay as invalid explained become. So can the flow rate calculation act as a control feature. When the calculated flow rate too high, due to flooding of the porous one carrier (for example, as a result of excessive sampling; or a result of a failed assay device due to Defects in the manufacture or damage in storage or in of use), the user can be warned and the assay result be discarded. Similarly, if the calculated flow rate is too low (e.g., due to under-sampling) Assay result be discarded. Thus, errors due to, for example, excessive or be avoided to low sampling.

in principle can any property of the fluid sample be measured to the speed and / or extent of progression the liquid to calculate its electrical capacity, conductivity or resistance. Of the porous carrier or other liquid transport carrier have a substance that has a detectable change in the presence the fluid sample passes. For example, nitrocellulose, commonly referred to as a porous support in lateral flow assay strips is used is impermeable (or essentially) if it is dry, but its impermeability is significantly reduced after wetting. So can the measurement or detection of the change in optical reflection or transmissivity of a nitrocellulose carrier wetting by a liquid sample are sufficient to determine the speed and / or extent of progression the fluid sample demonstrated.

Preferably have the means for calculating the speed and / or the extent the progress of the fluid sample, applied to the liquid transport carrier are, an optical detection system. Such an optical Detection system will typically generate one or more signals (Advantageously, electrical signals) in a manner based on the rate and / or extent of fluid sample progression responding. In a preferred embodiment, a suitable optical system at least two light sources and at least one Photodetector on, or vice versa, at least one light source and at least two photodetectors in order to be able to make optical measurements at least two spatially perform separate zones of the liquid transport carrier.

in principle can the light source outside of the assay result reader be, e.g. Ambient light. However, this is extremely likely Introduce fluctuation, and it is therefore very preferable that: (a) the assay result reading device equipped with at least one integral light source (LED's were considered special suitably found in this regard); and (b) the assay result reading device with a housing or fairing, which is essentially ambient light from the entrance to the interior of the reading device excludes or at least severely limited. For the present purpose is a housing or a fairing, they consider that they are essentially ambient light excludes if less than 10%, preferably less than 5% and most preferably less than 1% of the visible light incident on the outside the device penetrates into the interior of the device.

One opaque synthetic plastic material such as polycarbonate, ABS, polystyrene, Polystyrene, high density polyethylene, or polypropylene, the one suitable light blocking pigment is suitable Choice for the use in the manufacture of the housing. An opening may be on the outside of the housing be provided with the inner space inside the housing in Compound stands: a test strip or similar porous carrier can through the opening introduced to perform an assay.

The fluid sample may per se have an optical property (e.g., color) which the optical detection and / or monitoring of their progression accessible along the liquid transport carrier. For example, a blood sample will be strong in the range of 400 nm Absorb 600 nm due to the presence of hemoglobin. alternative this may be the liquid sample before application to the liquid transport carrier with an easily detectable substance (e.g., a dye, fluorochrome or similar) which does not interfere with the performance of the assay, but the detection (in particular optical detection) of the speed and / or extent the progress of the fluid sample facilitated.

In yet another arrangement is the liquid transport carrier with an easy-to-detect substance equipped by the liquid sample is transported. Again, a dye, fluorochrome or the like suitable in this regard. The easily detectable substance may be suitably solvable on a porous carrier or similar be immobilized so that they are in contact with the fluid sample can be released. The easily detectable substance can e.g. a colored substance that does not interfere with the assay. In a preferred embodiment the simply detectable substance is a particulate label, attached to a mobile specific binding reagent (with specific Tie for the analyte) and the detection of this label in a detection zone forms an essential feature of the assay.

The particulate Marking can be any suitable for this purpose including colored latex, a dye sol or gold particles. alternative this can be the particulate Marker have a fluorophore that emits through a LED Radiation of a suitable wavelength can be excited.

The preferred optical detection system comprises at least one light source and at least one photodetector (such as a photodiode). Preferred light sources are light-emitting diodes or LEDs. Reflected light and / or transmitted light can be measured by the photodetector. For the purposes of this disclosure, reflected light means that light from the light source is reflected by the porous carrier or other liquid transport carrier onto the photodetector. In this situation, the detector is typically provided on the same side of the carrier as the light source. Transmitted light refers to light passing through the carrier, and typically the detector is provided on the opposite side of the carrier to the light source. For the purposes of a reflectance measurement, the carrier may be equipped with a sub-layer such as a white reflective MYLAR ^® plastic layer. Thus, light from the light source falls on the support, some is reflected from its surface and some penetrates into the Trä ger and is reflected at any depth up to and including the depth at which the reflective layer is provided. Thus, a reflection type measurement actually involves the transmission of light through at least a portion of the thickness of the porous support.

In an embodiment has the reader a housing in which at least two light sources (e.g., LED's) and respective ones Photodetectors are included which are arranged to receive light from to record the LEDs.

A the light source illuminates a first upstream zone on the liquid transport carrier, and another light source illuminates a second, downstream one Zone on the liquid transport carrier, and respective photodetectors are provided to receive light from the reflected and / or transmitted to respective zones, the amount of such light that reflects and / or transmits will, depends whether the liquid sample (optional together with any light-absorbing or light-emitting Substance that is transported) reaches the relevant zone (s) Has.

In a particularly preferred embodiment has the assay result reading device three light sources, each first, second and third zones of the liquid transport carrier, and the flow rate the fluid sample between at least two of the zones is measured.

suitably is one of the zones from which measurements are made in the calculation of flow velocity also a zone, from the measurements to determine the result of the assay, for example, the first zone may be a Zone in the analyte-specifically labeled binding reagent immobilized if analyte is present in the sample. A such zone may be referred to as a test crown.

Desirably is one of the zones from which measurements in the calculation of flow velocity also a zone from the control measurements to the purpose of getting a control value used to determine if the assay was performed properly. Such a zone may be referred to as a control zone.

It is advantageous if there is a zone from the measurements in the Calculation of the flow velocity which is also a zone from the measurements in the Calibration of the assay result reader. Such Zone can be referred to as a reference zone.

It is desirable if the components of the assay reader, in the detection and / or quantification of the analyte of interest are also used in the Calculation of the flow velocity the liquid be used. This confers advantages of simplicity and economy that especially for a disposable device desirable are. In particular, a preferred assay result reader has an optical Detection system for detecting the presence and / or amount of the analyte of interest, and the same optical detection system is used to make measurements for the purpose of calculating flow velocities perform.

In a particularly preferred embodiment receives the assay score reader Measurements from a control zone, a reference zone and a test zone, the control zone downstream from the reference zone, which in turn is downstream of the test crown (i.e., the reference zone lies between the test and control zones). The reference zone allows, inter alia, the measurement an optical property (e.g., reflection and / or transmissivity) of the liquid transport carrier when it is wet (e.g., a wetted porous support). Suitably the results obtained from the test and control zones normalized relative to the reference zone, and taken into account and compensates for any variations in optical property the sample. This is especially important when biological samples, urine, which are used in the composition (e.g., concentration) can vary widely and therefore vary in color and color intensity.

The casing of the assay result reader typically has an opening on, making a test strip detachable in the case introduced and (preferably) in the housing can intervene. The case is configured such that ambient light, which is the interior of the Reading device is reached, is limited to an absolute minimum. Desirably are suitable alignment and fastening means within the housing provided so that the test strip remains in a fixed position, when he introduced is. The light sources are arranged in the housing such that if the test strip was inserted correctly, the light sources properly aligned with the particular zones to be measured are.

The assay test strip may be any conventional lateral flow assay test strip, as in U.S. Pat EP 291 194 or US 6,352,862 disclosed. The test strip preferably comprises a porous support containing a particulate-labeled specific binding reagent and an unlabeled specific binding reagent. The light sources and corresponding photodetectors are preferably aligned such that during use, light from the light source or sources falls onto the respective regions on the porous support and is reflected or transmitted to the respective photodetectors. The photodetectors produce a current that is approximately proportional to the amount of light that falls on them, which is then passed through a resistor to produce a voltage. The amount of light reaching the photodetector depends on the amount of colored particulate label present and thus on the amount of analyte. Thus, the amount of analyte present in the sample can be determined. This method of optical determination of the analyte concentration is described in more detail in US Pat EP 653 625 described.

Alternatively, instead of using a test strip having a lateral flow porous support, as in US Pat EP 291 194 a test strip with binding reagents arranged in a capillary could be used as described in US Pat US 6,113,885 disclosed.

Around an assay measurement using an assay result reader in accordance with Performing some of the preferred features becomes a test strip in the reader introduced, and a fluid sample will follow added to the sample receiving section of the test strip. alternative this can be a liquid sample first applied to the test strip, and the strip becomes subsequently in the reader introduced. The sample travels along the porous support and reaches a first one Zone, typically the test crown. When sample is added to the strip, becomes a colored one. particulate Marker resuspends and migrates along the carrier the liquid. When the liquid front the sample reaches the first zone, finds a reduction in the Light intensity, which reaches the photodetector instead, because the colored particulate mark absorbs some of the light. This change in reflected or transmitted light intensity is recorded. In practice, a greater amount of the particulate label in the initial liquid front as in the subsequent liquid present. If over it In addition, a binding reaction in the test crown due to the presence of analyte, the particle marking tends to occur in to remain on the test crown. So will the shape of the resulting observed voltage-time profiles depend on whether the zone is a test, Control or reference zone. For a three-zone system will be three voltage-time profiles for every Zone added, with a time delay due to the fact that the measurement zones are spatial are separated from each other and so is the time the liquid front needed to reach the first zone is less than what is needed to reach the second, etc.

Out the analysis of the voltage-time profiles for the respective zones and with the knowledge of the distance between the zones can speed the fluid flow be determined. By using a simple algorithm can the final assay measurement will be discarded if the calculated flow rate was determined to be too long or too high.

In a typical embodiment the assay result reading device will typically continue to be one or more of the following: a central processing unit (CPU) or microcontroller; two or more LEDs; two or more photodiodes; a Power source; and connected electrical circuits. The power source can be a battery or any other suitable power source (e.g., a photovoltaic cell). The CPU is typical programmed to determine if a calculated speed and / or extent of Progression of the fluid sample within predetermined limits.

Suitably, the assay score reader will have a way of displaying the result of the assay to the user. This can for example take the form of an acoustic or optical signal. Desirably, the device will have an optical display to indicate the assay result. This may simply take the form of one or more LED's or other light sources, such that the illumination of a particular light source or a combination of light sources conveys the necessary information to the user. Alternatively, the device may be equipped with an alphanumeric or other display, such as an LCD. In addition, or as an alternative to displaying the test result, the device may also indicate to the user or otherwise indicate whether the calculated rate and / or extent of fluid sample progression are within predetermined acceptable limits and thus whether the result of the particular assay should be discarded or not. If the reader determines that a particular assay result should be discarded, it may prompt the user to repeat the assay. displays, which are suitable for displaying this type of information are known in the art and disclosed, for example, in WO 99/51989.

An embodiment of an assay result reading apparatus in accordance with the present disclosure is disclosed in U.S. Pat 1 shown.

The reader is about 12 cm long and about 2 cm wide and is generally finger or cigar shaped. In preferred embodiments, the housing is no larger than about 12 cm long, about 2.5 cm wide and about 2.2 cm high. However, any suitable form may be used, such as a credit card-shaped reader. The device has a housing 2 formed of opaque plastic material (eg polycarbonate, ABS, polystyrene, high density polyethylene or polypropylene or polystyrene containing a suitable light blocking pigment such as carbon). At one end of the reader is a narrow slot or opening 4 provided, through which a test strip (not shown) can be inserted into the reading device.

On its upper side, the reader has two oval-shaped openings. An opening houses the screen of a liquid crystal display 6 indicating information to the user, eg the results of an assay, in a qualitative or quantitative manner. The other opening houses an ejection mechanism 8th which, when actuated, forcibly ejects an inserted assay device from the assay result reading device.

The assay device for use with the reader is a generally conventional lateral flow test stick, eg of the type shown in U.S. Pat US 6,156,271 . US 5,504,013 . EP 728,309 or EP 782 707 is disclosed. The assay device and a surface or surfaces of the slot in the reader into which the assay device is inserted are shaped and dimensioned such that (1) the assay device can only be successfully inserted into the reader in the proper orientation; and (2) there is a precise three-dimensional orientation of the reader and an inserted assay device that ensures that the assay result can be properly read by the reader.

A suitable assay device / reader-device combination that exhibits this precise three-dimensional orientation is shown in U.S. Patent No. 5,376,830 EP 833,145 disclosed.

If An assay device inserted properly into the reader becomes a switch closed, the reader from a "sleep mode which represents the normal state taken by the reader which reduces energy consumption.

Enclosed within the housing of the reader (and therefore in 1 not visible) are a variety of other components that are shown schematically in 2 are shown.

With reference to 2 the reader has three LEDs 10a . 10b and 10c on. When a test strip is inserted into the reader, each LED is on 10 aligned with a respective zone of the test strip. LED 10a is aligned with the test crown, LED 10b is aligned with the reference zone and LED 10c is aligned with the control zone. Respective photodiodes 12 detect light reflected from the various zones and generate a current whose magnitude is proportional to the amount of light incident on the photodiodes 12 is. The current is converted into a voltage, through a damper 14 attenuated and an analog-to-digital converter (ADC, 16 ). The resulting digital signal is through a microcontroller 18 read.

In a simple arrangement, a separate photodiode is provided to detect from each zone (ie the number of photodiodes corresponds to the number of zones from which reflected light measurements are made). The arrangement in 2 is more complicated and preferred. Two photodiodes 12 are provided. A photodiode detects light reflected from the test zone and some light reflected from the reference zone. The other photodiode 12 detects some of the light reflected from the reference zone and the light reflected from the control zone. The microcontroller 18 switches the LEDs 10 one at a time, so that only one of the three zones is illuminated at any given time - in this way, the signals generated by light reflected from the respective zones can be distinguished on a time basis.

2 further shows schematically the switch 20 which is closed by inserting an assay device into the reader, and the microcontroller 18 activated. Although in 2 not shown, the device further comprises a power source (typically one or two button cells) and an LCD device connected to the output of the microcontroller 18 responding.

In use, a dry test swab (ie, prior to contacting the sample) is inserted into the reader which closes the switch 20 , which activates the reader device, which then performs an initial calibration. The intensity of the light output from different LEDs is rarely identical. Likewise, it is unlikely that the respective photodetectors have identical sensitivities. Because such variations could interfere with the reading of the assay, an initial calibration is performed in which the microcontroller compensates for the length of time each of the three LED's illuminates, such that the measured signal from each of the three zones (test, reference and control ) is approximately equal and in an appropriate operating position in a linear region of the response profile of the system (so that a change in the light intensity reflected from the different zones provides a directly proportional change in the signal).

To performing of the initial one Eichens leads the device through another, fine oak by. This includes measuring ("Gauge value") of reflected Light intensity for every Zone during the test stick is dry, a - subsequent measurements ('Test values') are by reference name to the calibration value for normalizes the respective zones (i.e., normalized value = test value / calibration value).

Around to carry out an assay becomes a sample receiving portion of the test stick with the liquid sample brought into contact. In the case of a urine sample, the sample receiving section be kept in the urine stream, or the urine sample will be in one container collected and the sample receiving section becomes short (for about 5-20 seconds) immersed in the sample. Sampling can be carried out while the test stick in the reader introduced or, less preferably, the stick can be short out of the reader for sampling removed and then back in the reader be introduced.

Then be Measurements of the reflected light intensity of one or more (preferably all three) of the zones started, typically after a specific one measured interval after inserting the test stick into the reader. Desirably The measurements are taken at regular intervals (e.g., in between 1-10 Second intervals, preferably in between 1-5 second intervals). The Measurements are considered a sequence of many measurements over short (10 milliseconds or less) periods, overlapping zone by zone, carried out, eliminating any effects due to ambient light intensity variation that in the interior of the case of the reader penetrates, be minimized.

3 Figure 12 is a graph showing the intensity of reflected light (arbitrary units) versus time detected from each of the three zones, using a sample that does not contain the analyte of interest. The profile for the test crown is indicated by crosses, that for the reference zone by circles, and that for the control zone by triangles.

considered the testron profile, there is an initial lag phase during the the liquid sample along the porous carrier emigrated. In this time span is the amount of light that passes through the test zone is reflected, substantially constant. If the Sample reaches the test zone drops the amount of reflected light sharply. This is primarily due to absorption of light through the colored particulate marking that passes through the fluid sample is transported back. However, some reduction in the reflected light intensity is possible just back wetting of the nitrocellulose porous carrier because dry nitrocellulose more reflected.

If the liquid front over the Moving the test zone, the amount of reflected light starts to increase, the colored label is placed downstream with the sample Transported test zone. The reflected light intensity returns not to the original one Amount back, because of the wetting of the nitrocellulose and because of a small amount the colored particulate Mark left behind will if the liquid progresses.

In general, similar profiles are shown by the reference and control zones, although these are downstream of the test zone and so on. In particular, the control zone profile does not return to its original amount of reflected light intensity due to the development of the "con trolllinie "(ie deposition of colored particulate label in the control zone).

The 4 is substantially similar and shows the profiles obtained using% normalized results (ie, test value divided by calculation value × 100). The profile is expressed in% of the calculation value versus time. The 4 Figure 4 shows that normalization of the test measurements from an initial calculation measurement reduces the variation in the signal from the test, reference and control zones (although again the control zone value remains low due to the deposition of labeled reagent in the control zone).

Around the flow rate the fluid sample along the porous carrier To calculate, the exemplary reading device compares the normalized Values from the test and control zones with the result of that of the reference zone, to arrive at a "relative attenuation of the reflected light intensity" (% A).

Typical% A profiles (versus time) for a sample containing a relevant analyte of interest are in 5 shown. A positive attenuation means that the zone in question reflects less light than the reference zone, whereas a negative attenuation means that the zone in question reflects more light than the reference zone.

Referring on the% A profile of the testrone it is obvious that the Testron signal initially strongly weakened is (relative to the reference zone) when the liquid sample (with colored particulate marking) reached the test crown, but not yet reached the reference zone Has. After about The fluid sample begins 35 seconds to reach the reference zone, and this leads to a sudden Waste in relative weakening the test crown. After about 40 seconds, the liquid front begins to leave the reference zone, causing an increase in reflection the reference zone leads and thus to an increase in the relative weakening of the Test zone. This weakens and finally reach a plateau, with a positive weakening of just under 30%, The test crown has some of the colored particulate markings due to the Trapped presence of the analyte of interest in the sample.

considered to get the profile for the control zone, it is obvious that there is an initial sharp drop (negative weakening) gives because the liquid sample reached the reference zone before the control zone. When the liquid sample begins to leave the reference zone before the control zone begins the relative negative weakening in the signal from the control zone to return to zero, and when the liquid samples has reached the control zone, the relative weakening becomes positive and reaches a plateau amount of about 15% due to the deposition of labeled reagent in the control zone to give a positive control result provide.

While in the testron result with the present exemplary reader compared to the reference zone result, it would be useful Alternative, the testron result with the control zone result to compare.

Generally the flow rate is spoken calculated by detecting the change in reflected light intensity associated with the arrival of the fluid sample is associated in a particular zone, and determining the time between the arrival of the fluid sample passed in the different zones. Specifically, the flow rate, as described below.

The Signal in all three zones will be independent of the position of the liquid measured on the test strip.

The signal attenuation at the test crown will be regarding the signal attenuation measured at the reference zone. When the liquid front on the test crown arrives, the signal attenuation will be relative to the reference zone change, because the liquid front has not yet reached the reference zone (it is downstream of the test zone arranged). Timing begins when the signal attenuation of the test zone relative to the reference zone greater than 10% is. It should be noted that the value of 10% the Indicates confidence level, including any margin of error, which is connected with the reading of the Messages, which in turn is performed by the depends on different measurement parameters, e.g. Test strips, optics. This can vary and may be for everyone appropriate value selected become.

The liquid then proceed into the reference zone, and if the signal attenuation of the Control zone relative to the reference zone is greater than minus 10% (-10%), considers the device that the liquid reaches the control zone has (the minus value reflects again that the control zone downstream of the test zone is arranged). When the signal attenuation of the Control zone opposite the reference zone is larger (i.e. positive) than zero, the device determines that the liquid has reached the control zone. So must the timekeeping by the Device does not necessarily correspond exactly to the time, too the liquid arrives in the respective zones.

Even though in this example, the reader the rate of passage of liquid between the test and control zones, it measures them for the signal coming from the reference zone was obtained. However, the arrival of liquid could be absolutely determined in the test and control zones (i.e. by measuring with respect the reference zone).

The reader is also programmed to indicate a test result as invalid when the fluid sample is detected in the control zone before being in the reference zone is detected because this indicates that the fluid sample is abnormal River way is followed.

Example 2

One single optical device is used to both the signal and the flow rate to determine. The maximum and minimum flow rates are respectively set at 5 and 40 s. So any sample that lasts longer than 40 s needed, discarded too slowly (due to under-sampling) Any sample that is faster than 5 s will be considered too fast discarded. The flow rate is determined by a number of factors including porosity, distance between control and test lines as well as any chemistry in the porous one Strip, which can modify the flow can be influenced.

The Time is determined and set to zero when the liquid reached the test line. The timer is then set and the time until the liquid the control line is reached is measured. As a further control check the device that the liquid flowed through the reference zone. Additionally, as another control feature, monitored the device also that the fluid through the test, reference and control zones flowed in this order before it a flow velocity measurement will accept as authentic even if they are the flow velocity range of between 5 and 40 s.

In other embodiments can Of course the upper and lower flow rate limits on a wide variety of values, in accordance with particular Properties of the test liquids and / or with the factors described above.

Claims (17)

Assay result reader for reading the result an assay performed using a liquid transport carrier, the device comprises: at least one light source that is capable Light incidence on at least one of two or more, spatially separated Zones on the carrier to emit; a photodetector arranged so that he is capable is to detect emitted light from each of the two zones and generate signals indicating the presence or absence a liquid sample in the respective zone; and a calculation circle, which responds to the signals to: the flow rate for a liquid, along the carrier flows, to calculate; the calculated flow rate with upper and lower limits; and to discard the assay result, if the calculated flow rate outside the upper and lower limits. Device according to claim 1, wherein the carrier a porous one carrier having. Device according to claim 1 or 2, wherein the at least one light source is a light emitting diode having. Device according to a the claims 1, 2 or 3, wherein the at least one photodetector is a photodiode having. Device according to a of the preceding claims, wherein the at least one light source at least two light sources and at least one photodetector comprises at least two photodetectors. Device according to claim 5, wherein: the first light source is capable of incident light on the first zone to emit, and the first photodetector detects light, that emanates from the first zone; and the second light source is capable of Light incident on the second zone to emit, and the second photodetector Detected light that emanates from the second zone. Device according to a of the preceding claims, wherein the at least one light source at least two light-emitting diodes and the at least one photodetector comprises at least two photodiodes having. Device according to a of the preceding claims, the signal being the presence or absence of a fluid sample in a zone based on the optical reflection, the transmissivity, or both, of the vehicle is calculated. Device according to a of the preceding claims, which continues to be a case having the at least one light source and the at least includes a photodetector. Device according to claim 9, the case is not bigger as about 12 cm long, about 2.5 cm wide and about 2.2 cm high. Device according to a of the preceding claims, wherein the at least one light source and the at least one photodetector are arranged within a range that is not larger as about 1 Square centimeter. Device according to claim 11, wherein the at least one light source and the at least one Photodetectors are located within an area that is not is larger as about 0.7 square centimeters. Device according to a of the preceding claims, wherein signals generated by the at least one photodetector a quantity of the analyte present in a zone, Show. Method for performing an assay for a analytes of interest in a fluid sample, the method includes: Arranging a liquid transport carrier in Referring to an assay score reader that assigns the carrier at least two spatially separate zones, the reader has a housing on, the at least one light source and at least one photodetector includes, and the carrier is arranged such that the at least one light source light incidence emitted on at least one of the zones, and so that light, the radiates from at least one of the zones, the photodetector falls; Instruct or insertion the fluid sample on / in the liquid transport carrier; To calculate the flow rate the fluid sample along the carrier in response to signals passing through the at least one photodetector which indicates the presence or absence of the fluid sample in a respective zone; and Determine if the calculated flow rate within predetermined acceptable limits. Method according to claim 14, further comprising discarding an assay result if the calculated flow rate is not within the predetermined acceptable limits. Method according to claim 14 or 15, wherein the test strip is at least partially within of the assay result reader is arranged. The method of claim 14, 15 or 16, wherein the assay result reader further comprises a second photodetector having at least one light source first, second and third light sources, the test strip having three spatially separated zones, and wherein: each light source is aligned with and laterally spaced from a corresponding test strip zone; the first photodetector is arranged to receive light radiating from the first zone and the second zone; and the second photodetector is arranged to receive light from the second zone and the third Zone radiates.